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Microstructural and rheological transitions in bacterial biofilms

Lookup NU author(s): Sam Charlton, Professor Thomas CurtisORCiD, Dr Jinju Chen, Dr Saikat Jana



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


© 2023 The Authors. Advanced Science published by Wiley-VCH GmbH.Biofilms are aggregated bacterial communities structured within an extracellular matrix (ECM). ECM controls biofilm architecture and confers mechanical resistance against shear forces. From a physical perspective, biofilms can be described as colloidal gels, where bacterial cells are analogous to colloidal particles distributed in the polymeric ECM. However, the influence of the ECM in altering the cellular packing fraction (ϕ) and the resulting viscoelastic behavior of biofilm remains unexplored. Using biofilms of Pantoea sp. (WT) and its mutant (ΔUDP), the correlation between biofilm structure and its viscoelastic response is investigated. Experiments show that the reduction of exopolysaccharide production in ΔUDP biofilms corresponds with a seven-fold increase in ϕ, resulting in a colloidal glass-like structure. Consequently, the rheological signatures become altered, with the WT behaving like a weak gel, whilst the ΔUDP displayed a glass-like rheological signature. By co-culturing the two strains, biofilm ϕ is modulated which allows us to explore the structural changes and capture a change in viscoelastic response from a weak to a strong gel, and to a colloidal glass-like state. The results reveal the role of exopolysaccharide in mediating a structural transition in biofilms and demonstrate a correlation between biofilm structure and viscoelastic response.

Publication metadata

Author(s): Charlton Samuel, Bible Amber, Secchi Eleonora, Morrell-Falvey Jennifer, Retterer Scott, Curtis Thomas, Chen Jinju, Jana Saikat

Publication type: Article

Publication status: Published

Journal: Advanced Science

Year: 2023

Volume: 10

Issue: 27

Print publication date: 26/09/2023

Online publication date: 31/07/2023

Acceptance date: 30/06/2023

Date deposited: 07/07/2023

ISSN (electronic): 2198-3844

Publisher: Wiley-VCH Verlag GmbH & Co. KGaA


DOI: 10.1002/advs.202207373


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